Fuse device and clip therefor



Oct. 14, 1941. c. L. scHucK FUSE DEVICE AND CLIP THEREFOR Filed June 5, 1941 V M a 2 w m T C r 2% epdw W &A [F Ms c H Patented Oct. 14, 1941 FUSE DEVICE AND CLIP THEREFOR Carl L. Schuck, Philadelphia, Pa., assignor to General Electric Company, a corporation of w York Application June 5, 1941, Serial No. 396,662

4 Claims.

The present invention relates to improvements in electrical fuse devices and to contact clips therefor.

Fuse devices designed for overcurrent protection in normally heavy current, high voltage systems usually embody a plurality of relatively fine fuse wires connected in parallel and enclosed within a cartridge tube. In certain instances, it may be preferred to connect a pair or more of smaller capacity cartridge fuse devices in' parallel rather than provide a unit containing the necessary number of parallel fusible conductors in a single large cartridge tube. If separate contact clips are provided for holding individual cartridge fuses in parallel connection, variations in the condition of the contact surfaces for the two devices, in the contact pressure of the two sets of fuse clips, in the relative alignment of the two sets of fuse clips, as well as other factors will effect a variance in the contact resistance between the two parallel connected fuse devices. The current will therefore divide unequally between the parallel fuses, and that connected in the lower resistance path would carry the greater share of the total current and melt first followed by the melting of the remaining fuse. It is obvious, therefore, that in the usual parallel arrangement of cartridge fuses, it has been necessary to derat the combination of the two fuses considerably below the level of twice the rating of one fuse. Such derating of the fuses is uneconomical and does not permit of accurate coordination of fuses throughout a system.

It is an object of he present invention to provide a new and improved plural fuse arrangement in which the above and other disadvantages of the prior art are overcome.

More specifically, it is an object of the present invention to provide a new and improved electric fuse arrangement including a plurality of parallel fuse cartridges and contact clips therefor, the fuses and the clips being so arranged that the unit may be rated for the full sum of the ratings for the plurality of fuse elements. It is a further object of the invention to provide a new and improved contact clip arrangement for an electrical fuse unit comprising a pfurality of cartridges connected in parallel, which clips will effect an adequatecurrent conductive path to the parallel elements and provide suflicient and substantially uniform conduction of heat from the various elements.

For a consideration of what I believe to be novel and my invention, attention is directed to the following description and the claims appended thereto taken in connection with the accompanying drawing.

Referring to the drawing, Fig. 1 is a side elevation of a fuse arrangement and contact clips therefor constructed in accordance with the present invention; Fig. 2 is a front view of the arrangement shown in Fig. 1; Fig. 3 is a top view of th arrangement shown in Fig. 1; and Fig. 4 is a cross-sectional view of Fig. 1 taken along the line 4-4.

As will be evident from the ensuing description, various features of the present invention are subject to modification and are suitable for employment in other forms of electrical circuit interrupting devices. Hence the embodiment shown in the drawing is for purposes of illustration only. In this embodiment the fuse support includes two insulators I0 and II disposed in spaced relationship and bolted or otherwise secured at one end to a suitable base i2. On the outer end of each of the insulators there is supported a terminal and contact clip assembly l3 having a projecting portion to which electric line conductors or leads may be secured by clamping devices I4.

An electric circuit interrupting element I5 is shown mounted at opposite ends in the clip assemblies E3. The present invention may be embodied to advantage in contact clip supports for mounting various forms of electric circuit interrupting devices, and it is not intended therefore that the invention be limited to any one particular form. However, the illustrated exemplary contact clip support is especially suited for the mounting of fuse devices having casings constructed of glass, porcelain, or other frangible material. Such a fuse device may, for example, be of the form shown in the United States Patent 2,188,816, issued January 30, 1940, in the name of W. K. Rankin, and assigned to the General Electric Company, the same assignee as the present application. Fuse devices of the forrz'i shown in the Rankin patent may be of consi-ierable size and weight, particularly when rlesigned for high current interrupting ratings. They include a fusible element, and an insulat= ing support therefor, embedded in a body of or granular quartz which is contained in a tubu= lar glass casing the opposite ends of which are closed by metallic terminal end caps or ferrules. A pair of such fuse cartridges is shown at it and ii, the ferrules at the opposite ends of which are conductively connected together by suitabl means. As shown in the drawing the fuse cartridge ferrules are rigidly secured together he means of bridging pieces i8 soldered or brazed therebetween forming an integral fuse unit is.

The contact assemblies 43 each include a first clip formed by a generally U-shaped spring member, the legs it of which define jaws for engaging with the ferrules of the inner fuse cartridge it and which jaws are backed by the legs of a further U-shaped spring member 2|. The members is and 2| are secured as by screws 22 to the base casting 24. The outer ends of the jaws iii are doubled back over the legs of spring 2i as indicated at 25, the extremities of which extend through wide slots provided in extensions 28 of the base casting 24. The jaw extensions 25 act to press the outer ends of the jaws i3 inwardly against the corresponding ferrule of the fuse device so as to insure a good current conducting relation therebetween and, further, provide an additional heat radiating surface from which the heat losses incident to the current carrying function of the fuse device may be dissipated.

While a uniform distribution of current is largely insured by the integral connection between the adjacent ferrules of the fuse elements, unequal heating of the two devices may occur unless provision is made for conducting heat in substantially similar proportions from both cartridges. Thus, in order to prevent overheating of the outer cartridge of the unit and premature melting of the fusible element thereof, contact clips are also provided for engaging with the ferrules of the fuse cartridge l'l. Extending outwardly from the opposite sides of the base casting 24 so as to straddle the inner fuse cartridge i6 is a pair of arms 28 which are secured together intermediate their ends by means of a U-shaped integral bridging piece 29 which piece is further.

connected to the base casting 24 by an arm 3| which extends generally parallel with the arms 28. Secured to the opposite sides of the bridging part 29 are similar fuse clip members 32 which are adapted to cooperatively engage with the opposite surfaces of the ferrule of fuse cartridge H. The fuse clip members 32 are backed by springs 33 which further insure a good current.

aasaiea thus not only insure an adequate current carrying capacity to the outer fuse element but also provide a considerable heat radiating surface for conducting heat away from the ferrules of the outer element at substantially the same rate at which heat is carried from the ferrules of the inner element 86 by the contact clip members it! and 2!.

Having described the principle of operation of my invention in what I consider to represent a preferred embodiment thereof, I desire to have it understood that the specific details shown are merely illustrative and that the invention may be carried out in other ways.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. In an electric fuse arrangement, a supporting structure having spaced terminals, a fuse device connected between said terminals and comprising a pair of cartridge fuses each having opposite end ferrules, the adjacent end ferrules of said fuses being conductively connected together, contact clips on said terminals for engaging the opposite end ferrules of one of said fuse cartridges, arms extending outwardly from said terminals, contact clips on said arms for engaging with the corresponding end ferrules of the other of said cartridge fuses.

2. In an electric fuse arrangement, a supporting structure including a terminal, an electric circuit interrupting device having a pair of conductively connected adjacent end ferrules, a resilient contact clip secured to said terminal for cooperatively receiving one of said ferrules, a second contact clip for cooperatively receiving the second of said ferrules and means for supporting the second of said clips on said terminal in a spaced relation from said first contact clip.

3. In an electric fuse arrangement, a supporting structure having a terminal, a fuse device having a pair of interconnected adjacent end ferrules, a contact clip secured to said terminal for cooperatively receiving one of said ferrules, a second contact clip for cooperatively receiving the second of said ferrules, and conductive arms secured to said terminal for straddling the ferrule received by said first contact clip and for supporting said second contact clip.

4. A fuse clip comprising a. supporting base, a pair of spring legs secured to said base forming jaws for receiving a first fuse ferrule therebetween, a second pair of spring legs mounted on said base independently of said first pair of spring legs forming a second pair of jaws to receive therebetween a second fuse ferrule conductively connected to said first fuse ferrule.

CARL L. SCHUCK. 

